After Japan bombed Pearl Harbor on
December 7, 1941, it was feared the Japanese might invade and occupy
the islands confiscating millions of dollars in U.S. currency. This
money could be used to finance the Japanese war effort. In the
summer of 1942, all normal U.S. paper money was exchanged with notes
identifying specific use for the Hawaii islands. In October 1944, restrictions were lifted on these notes allowing
them to be used as normal U.S. currency.

-- Series of 1935 --

-- Series of 1934 --

-- For Armed Forces use in Europe and North Africa --

As with the Hawaii notes, there was a
concern if the German military confiscated large amounts of U.S.
Currency, they would use it. These notes would have been invalidated
if this occurred. These were mostly used during the invasion of
North Africa and Sicily.